The study proposes to use conventional and newly developed radiopharmaceuticals to study both tumor growth and the response to medication. Results are checked against models evolved to describe these events. An active area of work is the elucidation of the necessary and sufficient conditions for various radiopharmaceuticals to exert an action or uptake in normal and neoplastic tissue. Thus, multiple analogues have been synthesized of bone imaging agents in order to determine the spatial and charge restrictions on their uptake. The effects of hormonal therapy are being studied on bone scans in men with prostatic carcinoma treated with diethylstilbestrol, and in women with metastatic breast carcinoma under therapy with tamoxifen. Synthesis of several new radiopharmaceuticals has been accomplished, in an effort to examine active sites of enzymes through the use of radiolabeled substrates or analogues.